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Detection of the Wolbachia protein WPIP0282 in mosquito spermathecae: implications for cytoplasmic incompatibility
John F Beckmann1, Ann M Fallon
1Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA. beckm098@umn.edu
Abstract:
Cytoplasmic incompatibility (CI) is a conditional sterility induced by the bacterium Wolbachia pipientis that infects reproductive tissues in many arthropods. Although CI provides a potential tool to control insect vectors of arthropod-borne diseases, the molecular basis for CI induction is unknown. We hypothesized that a Wolbachia-encoded, CI-inducing factor would be enriched in sperm recovered from spermathecae of female mosquitoes. Using SDS-PAGE and mass spectrometry, we detected peptides from the 56 kDa hypothetical protein, encoded by wPip_0282, associated with sperm transferred to females by Wolbachia infected males. We also detected peptides from the same protein in Wolbachia infected ovaries. Homologs of wPip_0282 and the co-transcribed downstream gene, wPip_0283, occur as multiple divergent copies in genomes of CI-inducing strains of Wolbachia. The operon is located in a genomic context that includes mobile genetic elements. The absence of wPip_0282 and wPip_0283 homologs from genomes of Wolbachia in filarial nematodes, as well as other members of the Rickettsiales, suggests a role as a candidate CI effector.
Insights
Researchers identified a specific Wolbachia protein (wPip_0282) present in sperm, which is crucial for inducing cytoplasmic incompatibility (CI) in mosquitoes. This finding advances understanding of CI and its potential for disease vector control.
Area of Science:
- Microbiology
- Genetics
- Entomology
Background:
- Cytoplasmic incompatibility (CI) is a reproductive mechanism in arthropods mediated by Wolbachia bacteria.
- CI is a potential tool for controlling insect vectors of diseases like malaria and dengue.
- The molecular mechanisms underlying CI induction remain largely unknown.
Purpose of the Study:
- To identify the Wolbachia-encoded factor responsible for inducing CI.
- To investigate the enrichment of CI-inducing factors in sperm of infected males.
Main Methods:
- Analysis of sperm from female mosquitoes using SDS-PAGE and mass spectrometry.
- Bioinformatic analysis of Wolbachia genomes to identify candidate genes.
Main Results:
- Peptides from a 56 kDa hypothetical protein (wPip_0282) were detected in sperm and ovaries of Wolbachia-infected mosquitoes.
- Homologs of wPip_0282 and wPip_0283 are present in CI-inducing Wolbachia strains and absent in non-CI strains.
- The wPip_0282/0283 operon is located near mobile genetic elements.
Conclusions:
- The wPip_0282 protein is a strong candidate for the CI-effector molecule.
- The presence of wPip_0282/0283 homologs correlates with CI induction in Wolbachia.
- This discovery opens avenues for developing novel strategies for insect vector control.
